Financial Instruments

The following is a summary of cash equivalents and available-for-sale securities as of the end of the periods presented:



	December 31, 2016									April 2, 2016
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Money market funds	$	366,460	$	—	$	—		$	366,460	$	232,698	$	—	$	—		$	232,698
Financial institution
securities	474,872		—		—			474,872		284,853		—		—			284,853
Non-financial institution
securities	295,848		541		(744		)	295,645		564,480		862		(230		)	565,112
Auction rate securities	10,500		—		(273		)	10,227		10,500		—		(523		)	9,977
Municipal bonds	55,028		331		(566		)	54,793		68,938		877		(133		)	69,682
U.S. government and
agency securities	176,583		7		(142		)	176,448		192,291		73		(71		)	192,293
Foreign government and
agency securities	94,783		—		(33		)	94,750		313,168		—		—			313,168
Mortgage-backed securities	1,264,983		5,906		(18,205		)	1,252,684		1,200,071		12,848		(5,380		)	1,207,539
Asset-backed securities	215,879		677		(703		)	215,853		216,068		1,151		(605		)	216,614
Debt mutual funds	101,350		—		(15,415		)	85,935		101,350		—		(9,449		)	91,901
Bank loans	130,029		1,102		(75		)	131,056		102,092		25		(102		)	102,015
Commercial mortgage-
backed securities	219,675		128		(3,561		)	216,242		207,847		432		(1,809		)	206,470
	$	3,405,990	$	8,692	$	(39,717	)	$	3,374,965	$	3,494,356	$	16,268	$	(18,302	)	$	3,492,322

The following tables show the fair values and gross unrealized losses of the Company’s investments, aggregated by investment category, for individual securities that have been in a continuous unrealized loss position for the length of time specified, as of December 31, 2016 and April 2, 2016:



	December 31, 2016
	Less Than 12 Months					12 Months or Greater					Total
(In thousands)	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Non-financial institution securities	$	69,567	$	(733	)	$	1,523	$	(11	)	$	71,090	$	(744	)
Auction rate securities	—		—			10,227		(273		)	10,227		(273		)
Municipal bonds	32,671		(537		)	1,730		(29		)	34,401		(566		)
U.S. government and
agency securities	82,785		(142		)	—		—			82,785		(142		)
Foreign government and
agency securities	14,976		(33		)	—		—			14,976		(33		)
Mortgage-backed securities	914,938		(15,537		)	118,236		(2,668		)	1,033,174		(18,205		)
Asset-backed securities	87,937		(561		)	11,380		(142		)	99,317		(703		)
Debt mutual funds	—		—			85,935		(15,415		)	85,935		(15,415		)
Bank loans	12,264		(75		)	—		—			12,264		(75		)
Commercial mortgage-
backed securities	151,331		(1,984		)	24,384		(1,577		)	175,715		(3,561		)
	$	1,366,469	$	(19,602	)	$	253,415	$	(20,115	)	$	1,619,884	$	(39,717	)



	April 2, 2016
	Less Than 12 Months					12 Months or Greater					Total
(In thousands)	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Non-financial institution securities	$	52,756	$	(230	)	$	—	$	—		$	52,756	$	(230	)
Auction rate securities	—		—			9,977		(523		)	9,977		(523		)
Municipal bonds	10,138		(44		)	3,867		(89		)	14,005		(133		)
U.S. government and
agency securities	84,024		(71		)	—		—			84,024		(71		)
Mortgage-backed securities	346,560		(3,916		)	114,285		(1,464		)	460,845		(5,380		)
Asset-backed securities	81,038		(502		)	20,793		(103		)	101,831		(605		)
Debt mutual funds	—		—			91,901		(9,449		)	91,901		(9,449		)
Bank loans	34,358		(31		)	42,832		(71		)	77,190		(102		)
Commercial mortgage-
backed securities	141,761		(878		)	2,150		(931		)	143,911		(1,809		)
	$	750,635	$	(5,672	)	$	285,805	$	(12,630	)	$	1,036,440	$	(18,302	)

As of December 31, 2016, the gross unrealized losses that had been outstanding for less than twelve months were primarily related to mortgage-backed securities and were due to the general rising of the interest-rate environment. However, the percentage of such losses to the total estimated fair value of the mortgage-backed securities was relatively insignificant. The gross unrealized losses that had been outstanding for more than twelve months were primarily related to debt mutual funds and mortgage-backed securities, which were primarily due to the general rising of the interest-rate environment and foreign currency movement.

The Company reviewed the investment portfolio and determined that the gross unrealized losses on these investments as of December 31, 2016 and April 2, 2016 were temporary in nature. These investments are highly rated by the credit rating agencies and there have been no defaults on any of these securities, and we have received interest payments as they become due. Additionally, in the past several years a portion of the Company's investment in the mortgage-backed securities were redeemed or prepaid by the debtors at par. Furthermore, the aggregate of individual unrealized losses that had been outstanding for twelve months or more was not significant as of December 31, 2016 and April 2, 2016. The Company neither intends to sell these investments nor concludes that it is more-likely-than-not that it will have to sell them until recovery of their carrying values. The Company also believes that it will be able to collect both principal and interest amounts due to the Company at maturity, given the high credit quality of these investments and any related underlying collateral.

The amortized cost and estimated fair value of marketable debt securities (financial institution securities, non-financial institution securities, auction rate securities, municipal bonds, U.S. and foreign government and agency securities, mortgage-backed securities, asset-backed securities, bank loans and commercial mortgage-backed securities), by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations without call or prepayment penalties.



	December 31, 2016
(In thousands)	Amortized Cost		Estimated Fair Value
Due in one year or less	$	839,365	$	839,380
Due after one year through five years	496,399		494,352
Due after five years through ten years	243,772		243,648
Due after ten years	1,358,644		1,345,190
	$	2,938,180	$	2,922,570

As of December 31, 2016, $1.95 billion of marketable debt securities with contractual maturities of greater than one year were classified as short-term investments. Additionally, the above table did not include investments in money market and mutual funds because these funds do not have specific contractual maturities.

Certain information related to available-for-sale securities is as follows:



	Three Months Ended						Nine Months Ended
(In thousands)	December 31, 2016			January 2, 2016			December 31, 2016			January 2, 2016
Proceeds from sale of available-for-sale securities	$	130,891		$	82,396		$	384,236		$	203,426
Gross realized gains on sale of available-for-sale securities	$	624		$	203		$	2,055		$	1,038
Gross realized losses on sale of available-for-sale securities	(679		)	(221		)	(1,284		)	(439		)
Net realized gains (losses) on sale of available-for-sale securities	$	(55	)	$	(18	)	$	771		$	599
Amortization of premiums on available-for-sale securities	$	8,034		$	6,906		$	22,209		$	20,417

The cost of securities matured or sold is based on the specific identification method.